Immunotherapy with combination therapy comprising an immunotoxin

ABSTRACT

Provided is a combination and a method of using combination therapy to treat tumor in an individual. An immunotoxin and an immunostimulator are administered to the individual, wherein the immunotoxin comprises a single chain variable region antibody fused to a PE38 truncated  Pseudomonas  exotoxin, and the immunostimulator comprises an anti-CD40 agonist antibody. The combination may further comprise a checkpoint inhibitor comprising one or more of an anti-PD-1 antibody and an anti-PD-L1 antibody.

CROSS-REFERENCE TO RELATED APPLICATIONS

This invention claims priority to U.S. Provisional Application No. 62/927,753 filed on Oct. 30, 2019 and U.S. Provisional Application No. 63/046,738 filed on Jul. 1, 2020, the contents of which are both incorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under R35CA197264 awarded by the National Institutes of Health. The government has certain rights in the invention.

SEQUENCE LISTING

A Sequence Listing accompanies this application and is submitted as an ASCII text file of the sequence listing named “155554_00570_ST25.txt” which is 8.77 KB in size and was created on Oct. 27, 2020. The sequence listing is electronically submitted via EFS-Web with the application and is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

This invention is related to the area of immunotherapy. In particular, it relates to combination regimens for treating tumors, and kits and medicaments for accomplishing them.

BACKGROUND OF THE INVENTION

In human tumors, epithelial growth factor receptor frequently undergoes gene rearrangements. The most common extracellular domain mutation, EGFRvIII, comprises a deletion of exons 2-7 of the EGFR gene. Aberrant signaling through EGFRvIII has been shown to be important in driving tumor progression, and often correlates with poor prognosis. EGFRvIII expression occurs in a considerable portion of individuals with glioblastoma. Glioblastoma is the most dismal malignant brain tumor among all primary brain and central nervous system tumors. The median survival time for glioblastoma patients with the current standard treatment is less than 15 months. EGFRvIII is also expressed in primary breast tumors where it contributes to cancer stem cell phenotypes in breast cancer. EGFRvIII expression was significantly correlated with pathological subtypes of lung cancer (squamous cell carcinoma vs. adenocarcinoma). EGFRvIII expression has also been reported to regulate phenotypic plasticity in ovarian cancer and, thereby, contribute to more aggressive disease. Thus, there is an urgent need to develop advanced and efficient therapeutic approaches to improve the poor survival outlook of glioblastoma patients as well as other tumors expressing EGFR (epidermal growth factor receptors, including EGFR and/or EGFRvIII).

Cluster of differentiation 40 (CD40) can be expressed by B cells, myeloid cells, and dendritic cells, which can act as antigen presenting cells to foster a T-cell dependent, myeloid cell dependent, cytotoxic antitumor response. Thus, anti-CD40 agonist antibodies are fundamentally and functionally different from antibodies which block negative immune checkpoints such as anti-CTLA-4 or anti-PD1 antibodies (also known as checkpoint inhibitors).

Many types of solid tumors exploit the PD-1 pathway to escape immune surveillance by upregulating their expression of PD-L1. PD-L1 can bind with PD-1 on tumor-specific T cells and other immune cells to reduce the proliferation of PD-1 positive cells, inhibit their cytokine secretion, and induce apoptosis. Checkpoint inhibitors have been developed to promote anti-tumor immunity, such as by antibody-mediated blockade of the PD-1/PD-L1 axis.

SUMMARY OF THE INVENTION

According to one aspect of the invention a method is provided for treating a tumor in a patient. An immunotoxin and an immunostimulator are administered to the patient having a tumor expressing EGFR. The immunotoxin comprises a single chain variable region antibody which binds to EGFRwt and EGFRvIII and which is fused to a truncated Pseudomonas exotoxin comprising PE38. The single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6. The immunostimulator is an anti-CD40 agonist antibody. The truncated Pseudomonas exotoxin comprising PE38 comprises an amino acid sequence shown in SEQ ID NO: 7 and may further comprise (at the C-terminus) a sequence comprising an amino acid sequence selected from the group consisting of KDEL (SEQ ID NO:14), RDEL (SEQ ID NO:15), KEEL (SEQ ID NO:16), KNEL (SEQ ID NO:17), or REEL (SEQ ID NO:18).

In another aspect of the invention, the method further comprises administering an immune checkpoint inhibitor, which binds to PD-1 or PD-L1. Thus, in this aspect the method comprises administering to an individual a therapeutically effective amount of: an immunotoxin comprising a single chain variable region antibody which binds to EGFRwt and EGFRvIII and which is fused to a truncated Pseudomonas exotoxin comprising PE38, an anti-CD40 agonist antibody, and a checkpoint inhibitor comprising one or more of an anti-PD1 antibody, anti-PD-L1 antibody, or antibodie fragments of PD-1 or PDL-1 antibodies.

According to another aspect of the invention a kit is provided for treating a tumor. The kit comprises an immunotoxin and an immunostimulator comprising an anti-CD40 agonist antibody. The immunotoxin comprises a single chain variable region antibody genetically fused to a truncated Pseudomonas exotoxin comprising PE38, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6. Such single chain variable region antibody has binding specificity for EGFRwt and EGFRvIII. The kit may further comprise a checkpoint inhibitor comprising one or more of an anti-PD1 antibody or anti-PD-L1 antibody.

Also provided is a medicament comprising an anti-CD40 agonist antibody and an immunotoxin for use in treating solid tumor, wherein the immunotoxin comprises a single chain variable region antibody genetically fused to a truncated Pseudomonas exotoxin comprising PE38, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6.

Also provided is a medicament comprising an anti-CD40 agonist antibody, an immunotoxin, and a checkpoint inhibitor for use in treating solid tumor, wherein the immunotoxin comprises a single chain variable region antibody genetically fused to a truncated Pseudomonas exotoxin comprising PE38, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6, and wherein the checkpoint inhibitor comprises one or more of an anti-PD1 antibody or anti-PD-L1 antibody.

These and other embodiments which will be apparent to those of skill in the art upon reading the specification provide the art with treatments methods, regimens, kits and agents for treating tumors expressing epidermal growth factor receptors, i.e., EGFRwt and/or EGFRvIII.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an experimental outline for assessing efficacy of treatment with immunotoxin (“D2C7-IT”), anti-CD40 agonist antibody (“CD40 mAb”), a regimen combining administration of D2C7-IT and an isotype control antibody (same isotype as CD40 mAb), a regimen combining administration of D2C7-IT and CD40 mAb, and a negative control comprising 2% murine serum albumin in PBS (2% MSA-PBS) in combination with isotype control antibody (also known as Vehicle Control).

FIG. 2 is a graph showing an intracranial CT-2A-dmEGFRvIII-FFLuc intracranial glioma model showing the effects of treatment comparing percent survival to days post implantation of tumor. As compared to Vehicle Control, a single dose of the D2C7-IT monotherapy (bold black line), anti-CD40 agonist antibody (anti-CD40) monotherapy (hyphenated line), and D2C7-IT+ anti-CD40 combination therapy (solid line) generated a statistically significant delay in tumor growth; with D2C7-IT+ anti-CD40 combination therapy showing a synergistic effect in delaying tumor growth.

FIG. 3 is a table summarizing the results from the experiment illustrated in FIG. 2 comparing treatment groups for median survival, mice remaining after 50 days post-implantation, and statistical significance when compared to treatment with either Vehicle Control or D2C7 (D2C7-IT) monotherapy or with anti-CD40 (αCD40) monotherapy.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have developed targeted immunotoxins (IT), D2C7-(scdsFv)-PE38 (D2C7-IT), by fusing the single chain variable fragment (scFv) from the D2C7 monoclonal antibody (mAb) with the Pseudomonas exotoxin A (PE), optionally fused to KDEL (SEQ ID NO:14) peptide (as described in U.S. Pat. Nos. 9,492,564 & 10,072,084). D2C7-IT reacts with both the wild-type epidermal growth factor receptor (EGFRwt) and the EGFR variant III (EGFRvIII), two proteins that are overexpressed in glioblastoma. The robust antitumor efficacy of D2C7-IT is mediated through PE in orthotopic glioma xenograft models in immunocompromised mice. In addition to direct tumor cell killing, the immunotoxin monotherapy induces a secondary antitumor immune response through the engagement of T cells. When the immunotoxin is administered in a combination regimen with an immunostimulator comprising anti-CD40 agonist antibody, improved and synergistic results are observed. Also, when the immunotoxin is administered in a combination regimen with an immunostimulator comprising anti-CD40 agonist antibody, and with a checkpoint inhibitor comprising an anti-PD-1 antibody and/or anti-PD-L1 antibody, improved and synergistic results are observed. These combinations are capable of invoking tumor-specific T cell immunity, and may improve clinical outcomes in individuals treated with the combination who have tumor expressing one or more of wild-type epidermal growth factor receptor (EGFRwt) and the EGFR variant III (EGFRvIII).

In one embodiment, the immunotoxin comprises a single chain variable region (scFv) that binds to EGFR comprising a VH domain comprising CDR1, CDR2 and CDR3 of SEQ NO:1, 2 and 3, respectively connected via peptide linker to a VL domain comprising CDR1, CDR2 and CDR3 of SEQ ID NO: 4, 5 and 6, respectively. For example, the carboxyl terminus of the D2C7 V_(H) domain (SEQ ID NO:11) is connected to the amino terminus of the domain (SEQ ID NO:12) by a 15-amino-acid peptide (Gly₄Ser)₃ linker (SEQ ID NO: 13), which contains a disulfide bond generated by cysteine residues that replace Ser44 of V_(H) and Gly100 of V_(L) (e.g., D2C7-(scdsFv)-PE38KDEL IT), as described in U.S. Pat. Nos. 9,492,564 & 10,072,084, the contents of which are incorporated by reference in its entirety with regard to the immunotoxin. The D2C7 (scdsFv) was fused to DNA or domains II and III of Pseudomonas exotoxin A, PE38, (SEQ ID NO:7). The PE38 can further be modified at the c-terminus with additional moieties.

Other moieties which can be attached to the immunotoxin include those which provide additional beneficial properties. For example, a KDEL (lys-asp-glu-leu; SEQ ID NO:14) tetra-peptide can be added at the carboxy-terminus of the protein to provide retention in the endoplasmic reticulum. Variants such as DKEL (SEQ ID NO:19), RDEL (SEQ ID NO:15), and KNEL (SEQ ID NO:17) which function similarly can also be used.

Tumors which can be treated with the combination regimen comprising the immunotoxin and the anti-CD40 agonist antibody, or the immunotoxin, anti-CD40 agonist antibody, and a checkpoint inhibitor comprising one or more of an anti-PD1 antibody or an anti-PD-L1 antibody (“combination therapy”) are any that react with the D2C7 antibody or binding fragment thereof (e.g., an antibody comprising the CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6, and as described in Zalutsky et al. Radioimmunotargeting of malignant glioma by monoclonal antibody D2C7 reactive against both wild-type and variant III mutant epidermal growth factor receptors. Nucl Med Biol. 2012; 39(1):23-34, or the D2C7-IT described herein) or that express on the surface of the tumor cells EGFR. These include but are not limited to those in which at least one EGFRvIII allele is present. These may be found in tumors of the breast, head and neck, brain (e.g., glioblastoma multiforme, or astrocytoma), lung, or other solid tumors. It may be desirable to determine the presence of such an allele prior to combination therapy. This can be done using an oligonucleotide-based technique, such as PCR, or using an immunological technique, such as immunohistochemistry. It may be desirable to determine the amount, fraction, ratio, or percentage of cells in the tumor which express EGFRwt and/or EGFRvIII. The more cells which express EGFR on their surfaces, the more beneficial such combination therapy is likely to be. Even tumors that express little to no EGFRvIII may be treated due to the ability of the immunotoxin to bind to wild-type EGFR. Optionally, tumors may be tested prior to treatment for reactivity with D2C7 antibody using a detectable moiety coupled to the antibody, and visualization methods standard in the art. The immunotoxin itself could be used as an immunohistochemistry agent, before treatment, during treatment, or after treatment. A secondary reagent could be used with the immunotoxin for detection. It could, for example, recognize the Pseudomonas component of the immunotoxin.

Each of the immunotoxin, anti-CD40 agonist antibody, and checkpoint inhibitor (anti-PD1 antibody or an anti-PD-L1 antibody) may be administered by any appropriate (e.g., given the location of the tumor, and health of the patient receiving the therapy) technique known in the art. These include intravenous, oral, intraperitoneal, sublingual, intrathecal, intracavitary, intramuscularly, infusion, and subcutaneously. Compartmental or localized delivery may be desirable to avoid cytotoxicity should normal tissues express EGFR. Suitable compartmental or localized delivery methods include, but are not limited to delivery via a catheter, intratumoral delivery, application to a surgically created tumor resection cavity, and delivery to tumor parenchyma.

Tumors which can be treated by the method of the present invention are any which express epidermal growth factor receptor (EGFR), whether wild type, EGFRvIII, or other variants. Preferably the tumor expresses the receptor in amounts far exceeding expression by normal tissues. The mechanism of high level expression may be by genetic amplification, or other alterations, whether genetic or epigenetic, or post-translational modification. Exemplary tumors which can be treated include without limitation: malignant gliomas, breast cancer, head and neck squamous cell carcinoma, and lung cancer. The EGFR was found to act as a strong prognostic indicator in head and neck, ovarian, cervical, bladder and oesophageal cancers. In these cancers, increased EGFR expression was associated with reduced recurrence-free or overall survival rates in 70% (52/74) of studies. In gastric, breast, endometrial and colorectal cancers, the EGFR provided more modest prognostic information, correlating to poor survival rates in 52% (13/25) (see, Nicholson R I, Gee J M, Harper M E. EGFR and cancer prognosis. Eur J Cancer. 2001 September; 37 Suppl 4:S9-15. doi: 10.1016/s0959-8049(01)00231-3. PMID: 11597399).

Checkpoint inhibitors that comprise anti-PD1 antibodies or anti-PDL1-antibodies or fragments thereof are known to those skilled in the art, and include, but are not limited to, cemiplimab, nivolumab, pembrolizumab, MEDI0680 (AMP-514), spartalizumab, camrelizumab, sintilimab, toripalimab, dostarlimab, and AMP-224. Checkpoint inhibitors that comprise anti-PD-L1 antibodies known to those skilled in the art include, but are not limited to, atezolizumab, avelumab, durvalumab, and KN035. The antibody may comprise a monoclonal antibody (mAb), chimeric antibody, antibody fragment, single chain, or other antibody variant construct, as known to those skilled in the art. PD-1 inhibitors may include, but are not limited to, for example, PD-1 and PD-L1 antibodies or fragments thereof, including, nivolumab, an anti-PD-1 antibody, available from Bristol-Myers Squibb Co and described in U.S. Pat. Nos. 7,595,048, 8,728,474, 9,073,994, 9,067,999, 8,008,449 and 8,779,105; pembrolizumab, and anti-PD-1 antibody, available from Merck and Co and described in U.S. Pat. Nos. 8,952,136, 83,545,509, 8,900,587 and EP2170959; atezolizumab is an anti-PD-L1 available from Genentech, Inc. (Roche) and described in U.S. Pat. No. 8217149; avelumab (Bavencio, Pfizer, formulation described in PCT Publ. WO2017097407), durvalumab (Imfinzi, Medimmune/AstraZeneca, WO2011066389), cemiplimab (Libtayo, Regeneron Pharmaceuticals Inc., Sanofi, see, e.g., U.S. Pat, No. 9,938,345 and 9,987,500), spartalizumab (PDR001, Novartis), camrelizumab (AiRuiKa, Hengrui Medicine Co.), sintillimab (Tyvyt, Innovent Biologics/Eli Lilly), KN035 (Envafolimab, Tracon Pharmaceuticals, see, e.g., WO2017020801A1); tislelizumab available from BeiGene and described in U.S. Pat. No. 8,735,553; among others and the like. Other PD-1 and PD-L1 antibodies that are in development may also be used in the practice of the present invention, including, for example, PD-1 inhibitors including toripalimab (JS-001, Shanghai Junshi Biosciences), dostarlimab (GlaxoSmithKline), INCMGA00012 (Incyte, MarcoGenics), AMP-224 (AstraZeneca/MedImmune and GlaxoSmithKline), AMP-514 (AstraZeneca), and PD-L1 inhibitors including AUNP12 (Aurigene and Laboratoires), CA-170 (Aurigen/Curis), and BMS-986189 (Bristol-Myers Squibb), among others (the references citations regarding the antibodies noted above are incorporated by reference in their entirities with respect to the antibodies, their structure and sequences). Fragments of PD-1 or PD-L1 antibodies include those fragments of the antibodies that retain their function in binding PD-1 or PD-L1 as known in the art, for example, as described in AU2008266951 and Nigam et al. “Development of high affinity engineered antibody fragments targeting PD-L1 for immunoPED,” J Nucl Med May 1, 2018 vol. 59 no. supplement 1 1101, the contents of which are incorporated by reference in their entireties.

Anti-CD40 agonist antibodies comprise (a) antibodies that bind to CD40 on the surface of a cell and stimulate CD40 signaling as a result of the binding; (b) can modulate tumor-associated macrophages' immunosuppressive effect on development of a T cell-mediated antitumor response; and (c) generally, comprise antibodies whose binding domains recognize an epitope in either the cysteine rich domain 1 (“CRD1”) region of CD40 (CREKQYLINSQCCSLCQPGQKLVSDCT-EFTETECLP; SEQ ID NO:8) or an epitope in or overlapping the N-terminal portion of cysteine rich domain 2 (“CRD2”) region of CD40 (CGESEFL-DTWNRETHC; SEQ ID NO:9). Typically, the antibody is a monoclonal antibody or chimeric or humanized antibody. For example, there are at least 3 anti-CD40 agonist antibodies used in human clinical trials including CP870.893 (selicrelumab, RO7009789, Hoffman-La Roche, https://www.genome.jp/dbget-bin/www_bget?dr:D11491), APX005M (Apexigen), JNJ-64457107 (Alligator Bioscience), CDX-1140H (Celldex Therapeutics, Vitale et al., Development of CDX-1140, an agonist CD40 antibody for cancer immunotherapy. Cancer Immunol Immunother 2019; 68:233-45. 10.1007/s00262-018-2267-0), ChiLob 7/4 (Johnson P, Challis R, Chowdhury F, et al., Clinical and biological effects of an agonist anti-CD40 antibody: a Cancer Research UK phase I study. Clin Cancer Res 2015; 21:1321-8. 10.1158/1078-0432.CCR-14-2355), SEA-CD40 (Seattle Genetics, Gardai S J, et al. Abstract 2472: SEA-CD40, a sugar engineered non-fucosylated anti-CD40 antibody with improved immune activating capabilities. Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr. 18-22; Philadelphia, Pa. Philadelphia (Pa.): AACR; Cancer Res 2015; 75(15 Suppl):Abstract nr 2472 10.1158/1538-7445.AM2015-2472), 2141-V11, and SGN40 (dacetuzumab, Seattle Genetics), (see, e.g., Piechutta M, Berghoff A S. New emerging targets in cancer immunotherapy: the role of Cluster of Differentiation 40 (CD40/TNFR5). ESMO Open. 2019; 4(Suppl 3):e000510. Published 2019 Jun. 12. doi:10.1136/esmoopen-2019-000510). These three anti-CD40 agonist antibodies bind to an epitope in CRD1 of CD40. Deleting the A1 domain of CRD1 (CREKQYLINSQC; SEQ ID NO:10,) resulted in a greater than 90% reduction in binding of SGN40 and ChiLob 7/4 and a total loss of binding for CP870.893. Also, while both human IgG isotypes IgG1 and IgG2 can contribute to agonistic activity of anti-CD40 antibodies, data suggests that IgG2 was the most active of the human isotypes in contributing to the agonistic activity. Further, CD40 agonist antibodies may include modifications to their Fc portion of the antibody which improve binding to FcγRIIb and which may increase agonist activity. Such modifications include amino acid substitutions or changes in glycosylation (e.g., defucosylation) as known to those skilled in the art. Combinations of anti-CD40 agonist antibodies may be used in combination with the immunotoxin.

The anti-CD40 agonist antibody and/or checkpoint inhibitor may be administered at the same time (e.g., concurrently), before (e.g., prior to), or after (e.g., subsequent to) the immunotoxin. Typically, the agents (the immunotoxin, anti-CD40 agonist antibody, and checkpoint inhibitor) will be administered within 30, 28, 21, 14, 7, 4, 2, 1 or 0 day(s) of each other. The agents may be given repeatedly, either serially or in a cycle of first agent, the second agent, and third agent (the terms “first”, “second”, and “third” are used to distinguish between the agents, such as in an order of administration) such as in the discretion of a medical professional. It may be advantageous but not necessary for the immunotoxin to be administered prior to the anti-CD40 agonist antibody, and the checkpoint inhibitor, but the reverse order may also be used. Priming of a cytotoxic T lymphocyte response by the immunotoxin may take from about 5 to about 14 days. Administration of the anti-CD40 agonist antibody may beneficially be commenced during or after the priming period. Administration of the checkpoint inhibitor may beneficially be commenced before, during, or after such priming period. Some clinical studies using anti-CD40 agonist antibody used a single administration, whereas other studies utilized a regimen comprising repeated administration (e.g., weekly intervals). The frequency, order of administration, doses and dosage regimen of each agent in the combination therapy can be determined by a physician, taking into account the medical literature, the health, age and sex of the individual, the cancer to be treated, the mode of administration and dosing schedule of the composition or combination therapy, and other relevant considerations.

For example, anti-CD40 agonist antibody may be administered to an individual in an amount and at a suitable frequency to be therapeutically effective. For example, the anti-CD40 agonist antibody may be administered in a single administration (e.g., in a range of from 0.01 mg/kg to 10 mg/kg). In another example, the anti-CD40 agonist antibody may be administered in multiple intervals (e.g., daily, weekly, biweekly, monthly) at one or more doses (e.g., ranging from 2 doses, 4 doses, 5 doses, 6 doses, 8 doses, 12 doses, or more). Such doses can range from 0.6 μg/kg to 60 μg/kg; 0.01 mg/kg to 5 mg/kg; 0.5 mg to total dose (after 4 administrations) of 2 mg; 0.03 mg/kg to 0.3 mg/kg, 1 mg to 16 mg; and 75 μg/kg to 2000 μg/kg. In a method of treatment provided herein, an immunotoxin may be administered to an individual in an amount and at a suitable frequency to be therapeutically effective.

For example, an immunotoxin may be administered once, twice weekly, once each week, once every 2 weeks, once every 3 weeks, once each month, once every two months, once every 3 months, once every 4 months, once every 5 months, or once every 6 months. Doses of immunotoxin that may be administered in the combination therapy may range from 10 ng/ml to 25,000 ng/ml, such as between 100 ng/ml to 1,000 ng/ml, 1000 ng/ml to 3000 ng/ml, 3000 ng/ml to 6000 ng/ml, 6000 ng/ml to 10,000 ng/nl, and 10,000 ng/ml to 25,000 ng/ml. In a method of treatment provided herein, a checkpoint inhibitor may be administered to an individual in an amount and at a suitable frequency to be therapeutically effective.

For example, the checkpoint inhibitor may be administered once, twice, once every certain number of days, once each week, once every 2 weeks, once every 3 weeks, once each month, once every two months, once every 3 months, once every 4 months, once every 5 months, or once every 6 months. Doses of the checkpoint inhibitor that may be administered in the combination therapy may range from 0.1 mg/kg to 10 mg/kg, such as between 0.5 mg/kg to 3 mg/kg, 2mg/kg to 3 mg/kg, 3 mg/kg to 6 mg/kg, and 6 mg/kg to 10 mg/kg. The checkpoint inhibitor may be administered in maintenance therapy, a length of time depending on assessment of clinical parameters for assessing response to therapy.

In addition to treatment with the immunotoxin and anti-CD40 agonist antibody, or immunotoxin, anti-CD40 agonist antibody, and checkpoint inhibitor, an individual with tumor may undergo further treatment regimens which may include one or more of surgical removal of the tumor, surgical reduction of the tumor, chemotherapy, biological therapy, radiotherapy. These modalities may be standard of care, depending on the disease state of the patient having tumor. The immunotoxin and anti-CD40 agonist antibody, or immunotoxin, anti-CD40 agonist antibody, and checkpoint inhibitor, may be administered before, during, or after the standard of care. The immunotoxin and anti-CD40 agonist antibody(s), or immunotoxin, anti-CD40 agonist antibody, and checkpoint inhibitor, may be administered after failure of the standard of care.

Kits may comprise, in a single divided or undivided container, the immunotoxin or its components or its encoding DNA and anti-CD40 agonist antibody or combination of anti-CD40 agonist antibody, and checkpoint inhibitor. Storage stability may vary between the three agents so separate vessels may be used. Optionally one or more of the agents may be lyophilized or frozen. A unitary composition comprising the immunotoxin (D2C7-IT) in combination with the anti-CD40 agonist antibody are also provided. The composition may further comprise the checkpoint inhibitor as described herein. The composition may be lyophilized or frozen.

Immunotoxin therapy can induce a secondary anti-tumor immune response, which is different from its direct killing mechanism, which needs the cooperation of the immune system. Since malignant tumors can comprise a heterogeneous mass, it is possible that some tumor cells can escape from the direct targeted attack of the immunotoxin therapy due to the lack of epitopes recognized by the immunotoxin. For this reason, the secondary anti-tumor immune response stimulated by the immunotoxin may play an important role in eliminating those tumor cells not directly targeted. However, it is discovered here that a combination therapy of immunotoxin and anti-CD40 agonist antibody, and the combination further comprising a checkpoint inhibitor, provides synergistic anti-tumor effect to achieve a synergistic therapeutic effect.

Administration of the immunotoxin in combination therapy can efficiently and directly kill cancer cells that express high levels of the targeted antigen through its unique cytotoxic mechanism. Cancer cells destroyed by localized immunotoxin therapy release tumor antigens and/or other neoantigens. These antigens can then be presented by the APCs, such as those activated by anti-CD40 agonist antibody, to host T cells in the local draining lymph nodes, which activate CTLs, in the presence of blockade of the PD1/PD-L1 pathway by checkpoint inhibitor, to migrate and eliminate the remaining or recurrent tumor cells expressing specific tumor antigens at the tumor site.

The above disclosure generally describes the present invention. All references disclosed herein are expressly incorporated by reference. A more complete understanding can be obtained by reference to the following specific examples which are provided herein for purposes of illustration only, and are not intended to limit the scope of the invention.

EXAMPLE 1

As an illustration of treatment of an individual having tumor with combination therapy comprising an immunotoxin (D2C7-IT) and an anti-CD40 agonist antibody, a standard experimental model of tumor in immunocompetent individuals was used. Established a mouse glioma line, CT-2A-D2C7, overexpressing mouse EGFRvIII and expressing firefly luciferase (“FFLuc”) (“CT-2A-dmEGFRvIII-FFLuc”). C57BL/6J mice (˜20 g, 6-8 weeks, female) were anesthetized and were implanted intracranially with a total of 2×10⁵ CT-2A-dmEGFRvIII-Luc mouse glioma cells. Five days post tumor implantation, mice underwent bioluminescence imaging of tumor, and were then randomized into different treatment groups (10 mice/group). Anti-mouse CD40 agonist monoclonal antibody (Clone FGK4.5/FGK45) was purchased from a commercial source. As shown in FIG. 1 , six days post tumor implantation the groups of mice were infused as follows. Group 1 received a negative control comprising 2% murine serum albumin in PBS (2% MSA-PBS) in combination with isotype control antibody (also known as Vehicle Control). Group 2 received anti-CD40 agonist antibody (300 μg total dose in 2% MSA-PBS; “CD40 mAb”). Group 3 received immunotoxin D2C7-IT (0.2 μg total dose in 2% MSA-PBS)+isotype control antibody. Group 4 received combination therapy comprising anti-CD40 agonist antibody (300 μg total dose in 2% MSA-PBS) and D2C7-IT immunotoxin (0.2 μg total dose). The different treatments were administered to the groups by convection-enhanced delivery (CED) at a rate of 0.5 μl/hour for 144 hours via osmotic mini-pumps. The antitumor response of intracranial (ic) tumors to treatment was assessed by measuring median survival of the treated individuals over the testing period. As shown in FIGS. 2 & 3 , the median survival (50% survival) for the control group, Group 1, was 16 days; for Group 2 treated with anti-CD40 agonist antibody monotherapy was 22 days; for Group 3 treated with D2C7-IT monotherapy was 30 days; and for Group 4 receiving both D2C7-IT and anti-CD40 agonist antibody was not yet reached after concluding the study at day 54. Thus, these data indicate that anti-CD40 agonist antibody can synergize with immunotoxin in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR or variant thereof such as EGFRvIII.

As shown in FIG. 3 , at conclusion of the study and using bioluminescence imaging for tumor detection, 2 out of 10 individuals treated with anti-CD40 agonist antibody monotherapy (Group 2) were tumor-free; 1 out of 10 individuals treated with D2C7-IT monotherapy (Group 3) were tumor-free; and 8 out of 10 individuals treated with both D2C7-IT and anti-CD40 agonist antibody (Group 4) were tumor-free. Thus, these data indicate that anti-CD40 agonist antibody can synergize with immunotoxin in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR or variant thereof such as EGFRvIII.

EXAMPLE 2

Using the standard experimental model of tumor in immunocompetent individuals as described in Example 1, illustrated is the treatment of an individual having tumor with combination therapy comprising an immunotoxin (D2C7-IT), an anti-CD40 agonist antibody, and a checkpoint inhibitor for the blockade of the PD1/PD-L1 pathway. Six days post tumor implantation, the groups of mice (10 mice per group) were treated as follows (with D2C7-IT and anti-CD40 agonist Ab being adminsitered intracranially, and anti-PD-1 mAb administered intraperitoneally). Group 1 received 2% murine serum albumin in PBS (2% MSA-PBS) in combination with isotype control antibodies for both anti-CD40 agonist antibody and the checkpoint inhibitor antibody (“Vehicle Control”, Table 1). Group 2 received immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with isotype control antibodies for both anti-CD40 agonist antibody and the checkpoint inhibitor antibody (“D2C7-IT”, Table 1). Group 3 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS)+isotype control antibody for the checkpoint inhibitor antibody (“αCD40”, Table 1). Group 4 received 2% MSA-PBS in combination with isotype control antibody for the anti-CD40 agonist antibody, and 250 μg of anti-PD-1 mAb (“αPD-1”, Table 1). Group 5 received the immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS) and isotype control antibody for the checkpoint inhibitor antibody (“D2C7-IT+αCD40”, Table 1). Group 6 received immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with isotype control antibody for anti-CD40 agonist antibody, and 250 μg of anti-PD-1 mAb (“D2C7-IT+αPD-1 mAb”, Table 1). Group 7 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS) and 250 μg of anti-PD-1 mAb ((“αCD40+αPD-1 mAb”, Table 1). Group 8 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS), 250 μg of anti-PD-1 mAb, and D2C7-IT immunotoxin (0.1 μg total dose) (“D2C7-IT+αCD40+αPD-1 mAb”, Table 1).

The antitumor response of each treatment was assessed by measuring the median survival of each treated group over the testing period. The median survivals were compared among the 8 treated groups, and results subject to statistical analysis as compared to the Vehicle Control, as shown in Table 1.

TABLE 1 Number surviving Comparison Median measured days post to Vehicle Treatment Group Survival tumor implant (Wilcoxon test) Vehicle Control 17.5 0/10 — D2C7-IT 24 1/10 0.0044 (**) αCD40 28.5 3/10 0.1334 αPD-1 23.5 3/10 0.0570 D2C7-IT + αCD40 >59.5 5/10 0.0016 (**) D2C7-IT + αPD-1 >70 6/10 0.0052 (**) αCD40 + αPD-1 >57 5/10 0.0007 (***) D2C7-IT + αCD40 + >75 9/10 <0.0001 (****) αPD-1

As shown in Table 1, the median survival (50% survival) of individuals receiving combination treatment comprising immunotoxin and anti-CD40 agonist antibody was significantly higher (51.5 days) than the median survival of individuals receiving monotherapy with with ether immunotoxin (24 days) or anti-CD40 agonist antibody (28.5 days). Likewise, the median survival for individuals receiving combination treatment comprising immunotoxin, anti-CD40 agonist antibody and checkpoint inhibitor was significantly higher (greater than 54 days) than the median survival of individuals treated with monotherapy with either immunotoxin (24 days) or anti-CD40 agonist antibody (28.5 days). Thus, these data indicate that immunotoxin can synergize with anti-CD40 agonsit antibody, and with both anti-CD40 agonist antoibody and checkpoint inhibitor, in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR or variant thereof such as EGFRvIII.

As shown in Table 1, at conclusion of the study and using bioluminescence imaging for tumor detection: 3 out of 10 individuals treated with anti-CD40 agonist antibody monotherapy (Group 3) were tumor-free; 1 out of 10 individuals treated with D2C7-IT monotherapy (Group 2) was tumor-free; 5 out of 10 individuals receiving a combination comprising D2C7-IT and anti-CD40 agonist antibody (Group 5) were tumor-free; and 9 out of 10 individuals receiving a combination comprising D2C7-IT, anti-CD40 agonist antibody, and checkpoint inhibitor (Group 8) were tumor-free. Thus, these data indicate that anti-CD40 agonist antibody and immunotoxin can synergize in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR or variant thereof such as EGFRvIII; and that anti-CD40 agonist antibody, immunotoxin, and checkpoint inhibitor can synergize in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR (EGFRwt or variant thereof such as EGFRvIII).

EXAMPLE 3

Using the standard experimental model of tumor in immunocompetent individuals as described in Examples 1 & 2, provided is another illustration of the treatment of an individual having tumor with combination therapy comprising an immunotoxin (D2C7), an anti-CD40 agonist antibody, and a checkpoint inhibitor for the blockade of the PD1/PD-L1 pathway. Six days post tumor implantation, the groups of mice (5 mice per group) were treated as follows (with D2C7-IT and anti-CD40 agonsat Ab being adminsitered intracranially, and anti-PD-L1 mAb administered intraperitoneally). Group 1 received 2% murine serum albumin in PBS (2% MSA-PBS) in combination with isotype control antibodies for both anti-CD40 agonist antibody and the checkpoint inhibitor antibody (“Vehicle Control”, Table 2). Group 2 received immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with isotype control antibodies for both anti-CD40 agonist antibody and the checkpoint inhibitor antibody (“D2C7-IT”, Table 2). Group 3 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS)+isotype control antibody for the checkpoint inhibitor antibody (“αCD40”, Table 2). Group 4 received 2% MSA-PBS in combination with isotype control antibody for the anti-CD40 agonist antibody, and 250 μg of anti-PD-L1 mAb (“αPD-L1”, Table 2). Group 5 received the immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS) and isotype control antibody for the checkpoint inhibitor antibody (“D2C7-IT+αCD40”, Table 2). Group 6 received immunotoxin D2C7-IT (0.1 μg total dose in 2% MSA-PBS) in combination with isotype control antibody for anti-CD40 agonist antibody, and 250 μg of anti-PD-L1 mAb (“D2C7-IT+αPD-L1”, Table 2). Group 7 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS) and 250 μg of anti-PD-L1 mAb ((“αCD40+αPD-L1”, Table 2). Group 8 received anti-CD40 agonist antibody (30 μg total dose in 2% MSA-PBS), 250 μg of anti-PD-L1 mAb, and D2C7-IT immunotoxin (0.1 μg total dose) (“D2C7-IT+αCD40+αPD-L1”, Table 2).

The antitumor response of each treatment was assessed by measuring the median survival of each treated group over the testing period. The median survivals were compared among the 8 treated groups, as shown in Table 2.

TABLE 2 Number surviving measured Treatment Group Median Survival days post tumor implant Vehicle Control 14 0/5 D2C7-IT 35 1/5 αCD40 23 0/5 αPD-L1 15 0/5 D2C7-IT + αCD40 47 2/5 D2C7-IT + αPD-L1 36 2/5 aCD40 + αPD-L1 40 2/5 D2C7-IT + αCD40 + >84  4/5 αPD-L1

As shown in Table 2, the median survival (50% survival) of individuals receiving combination treatment comprising immunotoxin and anti-CD40 agonist antibody was significantly higher (47 days) than the median survival of individuals receiving monotherapy with either immunotoxin (35 days) or anti-CD40 agonist antibody (23 days) alone. Likewise, the median survival for individuals receiving combination treatment comprising immunotoxin, anti-CD40 agonist antibody and checkpoint inhibitor was significantly higher (greater than 84 days) than the median survival of individuals treated with monotherapy with either immunotoxin (35 days) or anti-CD40 agonist antibody (23 days) alone. Thus, these data indicate that immunotoxin can synergize with anti-CD40 agonist antibody, and with both anti-CD40 agonist antibody and checkpoint inhibitor, in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR comprising EGFRwt and/or variant thereof such as EGFRvIII.

As shown in Table 2, at conclusion of the study and using bioluminescence imaging for tumor detection: 0 out of 5 individuals treated with anti-CD40 agonist antibody monotherapy (Group 3) were tumor-free; 1 out of 5 individuals treated with D2C7-IT monotherapy (Group 2) was tumor-free; 2 out of 5 individuals receiving a combination comprising D2C7-IT and anti-CD40 agonist antibody (Group 5) were tumor-free; and 4 out of 5 individuals receiving a combination comprising D2C7-IT, anti-CD40 agonist antibody, and checkpoint inhibitor (Group 8) were tumor-free. Thus, these data indicate that anti-CD40 agonist antibody and immunotoxin can synergize in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR; and that anti-CD40 agonist antibody, immunotoxin, and checkpoint inhibitor can synergize in generating a durable and long lasting antitumor immune response against malignant tumor expressing EGFR comprising EGFRwt or variant thereof such as EGFRvIII.

EXAMPLE 4 Construction, Expression, and Purification of D2C7-(scdsFv)-PE38KDEL Immunotoxin.

The carboxyl terminus of the D2C7 V_(H) domain was connected to the amino terminus of the V_(L) domain by a 15-amino-acid peptide (Gly₄Ser)₃ linker. In order to obtain a stable IT, it is essential to ensure that during renaturation V_(H) is positioned near V_(L). This was achieved by mutating a single key residue in each chain to cysteine, for the stabilizing disulfide bond to form. On the basis of predictions using molecular modeling and empirical data with other dsFv-recombinant ITs, we chose one amino acid in each chain to mutate to cysteine. These are residues 44 in the framework region 2 (FR2) of V_(H) and 100 in the FR4 of V_(L) (according to the Kabat numbering). Thus, we prepared an Fv that contains both a peptide linker and a disulfide bond generated by cysteine residues that replace Ser44 of V_(H) and Gly100 of V_(L). The D2C7 (scdsFv) PCR fragment was then fused to DNA for domains II and III of Pseudomonas exotoxin A. The version of Pseudomonas exotoxin A used here, PE38KDEL, has a modified C terminus which increases its intracellular retention, in turn enhancing its cytotoxicity. The D2C7-(scdsFv)-PE38KDEL was expressed in E. coli under the control of T7 promoter and harvested as inclusion bodies. 

1. A method of treating a solid tumor expressing one or more of EGFRwt and EGFRvIII in an individual, comprising: administering to the individual a therapeutically effective amount of an immunotoxin comprising a single chain variable region antibody fused to a Pseudomonas exotoxin comprising PE38, wherein the single chain variable region antibody comprises CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6; and administering a therapeutically effective amount of an anti-CD40 agonist antibody to the individual.
 2. The method of claim 1, further comprising administering to the individual—a therapeutically effective amount of a checkpoint inhibitor comprising one or more of an anti-PD1 antibody or anti-PD-L1 antibody.
 3. The method of claim 1, wherein the tumor is a malignant glioma.
 4. The method of claim 1, wherein the tumor is breast cancer.
 5. The method of claim 1, wherein the tumor is head and neck squamous cell carcinoma.
 6. The method of claim 1, wherein the tumor is lung cancer.
 7. The method of claim 1, wherein the immunotoxin is administered directly to the tumor.
 8. The method of claim 1, wherein the anti-CD40 agonist antibody is administered within 30 days of administering the immunotoxin.
 9. The method of claim 1, wherein the anti-CD40 agonist antibody is administered within 7 days of administering the immunotoxin.
 10. The method of claim 1, wherein the anti-CD40 agonist antibody is administered concurrently with administering the immunotoxin.
 11. The method of claim 1, wherein the PE38 truncated Pseudomonas exotoxin is fused to a KDEL (SEQ ID NO:14) peptide.
 12. The method of claim 2, wherein the checkpoint inhibitor is administered within 30 days of administering the immunotoxin.
 13. The method of claim 2, wherein the checkpoint inhibitor is administered within between 7 and 14 days of administering the immunotoxin.
 14. A kit for treating a tumor, comprising: an immunotoxin comprising a single chain variable region antibody fused to a PE38 truncated Pseudomonas exotoxin, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6; and an anti-CD40 agonist antibody.
 15. The kit of claim 14, wherein the PE38 truncated Pseudomonas exotoxin is fused to a KDEL peptide comprising SEQ ID NO:
 14. 16. The kit of claim 14, further comprising a checkpoint inhibitor comprising one or more of an anti-PD-1 antibody and an anti-PD-L1 antibody.
 17. A composition comprising an immunotoxin comprising a single chain variable region antibody fused to a PE38 truncated Pseudomonas exotoxin, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 1-6; and an anti-CD40 agonist antibody.
 18. The composition of claim 17, further comprising a checkpoint inhibitor comprising one or more of an anti-PD-1 antibody and an anti-PD-L1 antibody. 